1. Technical Field
The present invention relates to a radiological image detection apparatus.
2. Background Art
Recently, a radiological image detection apparatus that utilizes a flat panel detector (FPD) for detecting a radiological image to generate digital image data has been put into practical use. The radiological image detection apparatus has been rapidly distributed because an image can be instantly confirmed as compared with an imaging plate configured by a photostimulable phosphor (accumulative phosphor). Various types of radiological image detection apparatus are available, one of which is known as an indirect conversion type.
The indirect conversion type radiological image detection apparatus includes a scintillator for generating fluorescence when exposed to radiation and a pixel array for detecting the fluorescence of the scintillator. The scintillator and the pixel array are disposed on, for example, individual substrates, respectively, and are bonded to each other through an adhesive layer. The radiation is converted into light by the scintillator and the fluorescence of the scintillator is converted into an electrical signal by the pixel array, and, as a result, digital image data is generated (see, for example, JP-A-2011-017683 corresponding to US 2011/006213 A1, and JP-A-2011-033562).
The scintillator is typically formed by a vapor deposition method using an alkali halide phosphor such as cesium iodide (CsI), and sodium iodide (NaI), and is configured by a group of columnar crystals formed by growing crystals of the phosphor into columnar shapes. The columnar crystals of the phosphor formed by the vapor deposition method do not contain impurities such as a binder, and also suppresses a diffusion of fluorescence by a light guide effect that guides the fluorescence generated in a columnar crystal in a growth direction of the crystal. Therefore, sensitivity of the radiological image detection apparatus and sharpness of an image can be improved.
A radiological image detection apparatus in which the scintillator and the pixel array are in close contact with each other without using the adhesive layer has also been known (see, for example, JP-A-2010-261720). In the radiological image detection apparatus disclosed in JP-A-2010-261720, a substrate for supporting the scintillator is flexible, and the scintillator and the pixel array is placed and an isolated space is also disposed between a substrate for supporting the scintillator and a substrate for supporting the pixel array. As the isolated space is depressurized, the substrate for supporting the scintillator is warped, and the scintillator is pressed by the pixel array. Therefore, the non-uniformity of image quality caused by the non-uniformity of the thickness of the adhesive layer is reduced.